Although a microscope may provide a very clear image of a very small portion of a surface, utilization of the microscope often requires the operator to be certain which small portion of the surface is being imaged. For optical microscopes, the operator may utilize a plurality of magnifications whereby the lowest magnification enables the desired area to be located, and the highest magnification enables that area to be closely observed. However, modern force microscopes, such as the atomic force microscope (AFM) and the interfacial force microscope (IFM), systematically move a very small probe over a surface and use a computer to produce an image representative of micron-level movement of the probe. Such devices are not capable of giving a low magnification view of the area under observation, and their probe tip is too small to observe with the naked eye or high magnification optical microscopes. If the tip position is not accurately determined, the location of the area under observation is not accurately determined. Other techniques must be used for the proper placement of such microscopes.
U.S. Pat. No. 5,650,614 of Yasutake et al discloses a system where an optical microscope is focused on a surface a distance from the probe of an AFM. The subject under test is placed under the optical microscope and examined at about 5.times. and then 50.times. so a bright spot can be centered in the optical axis. The subject is then translated the known distance between the microscopes so it is under the probe of the AFM. Aligning accuracy is stated to be on the order of 100 .mu.m. The accuracy of this device depends on the accuracy with which the position of the probe is determined.
U.S. Pat. No. 5,689,063 of Fujiu et al. discloses another method for aligning AFM by having a specially designed AFM axially aligned with the objective lens of an optical microscope. This patent requires custom construction of both the force microscope and the optical microscope.